Automatic motor control.



S. H. KANMAGHER.

AUTOMATIC MOTOR CONTROL.

APPLIOATION FILED OUT. 15, 1906.

Patented June 1, 1909.

Witnesses:

Inventor Sam H Kanmacher,

UNITED STATES PATENT OFFICE.

SAM H. KANMACHER, OF SOHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION NEW YORK.

AUTOMATIC MOTOR con'riaon To all whom it may concern:

Be it known that I, SAM H. KANMACHER, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new, and useful Improvements in Automatic Motor Controls, of which the following is a specification.

My invention relates to the automatic control of devices driven by electric motors, and

is particularly applicable to the control 0t,

electrically-actuated valves and similar devices. With such devices it is ordinarily desired that means should be provided for antomatically breaking the motor circuit when the driven member reaches either of its extreme positions, and it is also frequently desirable to rovide means for automatically breaking t e motor circuit when the driven member reaches a certain position predetermined by the operator. F or this latter urpose means have been rovided heretoore, .comprising a control ing handle and means actuated by the movement of the driven member for breaking the motor circuit when the member reaches a position bearing a certain relation to the position of the controlling handle.

My invention consists in providing means for securing in a simple manner an automatic breaking of the motor circuit, bothupon the driven member reaching either extreme in its range of movement, and also, when desired upon the drivenmember reaching an intermediate positlon determined by the operator. To accomplish this result, I provide a controlling switch forthe motor arranged to return automatically to oii- Josition when released means for retaining .t e switch in an operative position, an overload-magnet in' series with the motor arranged to release the switch from the retaining means when the driven member reaches either extreme in its range of movement, thereby stalling the motor and increasing the motor current above the normal limit, and means controlled by theposition of the member also operatively related to the retaining means forthe switch. I L I My invention will best be understood by reference to the accompanying drawing, in

' which A represents the armature and a the field of an electric motor which is connected Specification of Letters latent. Application filed October 15, 1806.

Patented June 1, 1909.

Serial No. 838,890.

through any s uitablespeed-reducing gearing to a valve or similar device B.

O represents the controlling switch for the motor, which is normally held in mid-position by the centering s rings -0 c.

(1 represents alatch or locking'the switch C in either of its operative positions, when the magnet D contro ling the latch, is energized.

E E represent magnetically-actuated switches or contactors, controlled by the switch C, and controlling the motor circuit.

F'represents an overload magnet in the motor circuit, controlling contacts in the circuitof switch 0.

G and H represent two resistances, which are connected across the source of current for the motor. These resistances are provided with contact members 9 and h, respectively, arranged to engage different points on the. two resistances. The contact 9 is carried by the valve-spindle, while the contact mom er h is manually controlled by the operator.

I represents a magnet, which is connected between the contacts h and g, forming, with the resistances H and G, a Wheatstonebridge connection. The contacts controlled by the magnet I are arranged to short-circuit the locking magnet D.

J represents an indicating device, such as a voltmeter, connected between one of the mains and contacts g, for indicating the position of the valve.

K represents a switch which, when 0 en, renders the magnet I inoperative by brea' ing the circuits of its winding and of its contacts. l

L represents leads to a source of current for the motor, and L represents leads to a source of current for the control-circuit, which may or maynot be the same source as that which supplies the motor.

The operation of the ap aratus shown is as follows: When contro ing switch C is moved to the right, a circuit is closed from the upper line-wire L throughmagnet D, switch C, magnet E, and contacts of overloadmagnet'F, to the lower line-wire L Magnet l) is consequently energized, so as todraw down its core and lock switch C- in position, while magnet E raises its contacts,

closing a circuit from line-wire L throu h the field and armature of motor A. T e motor, consequently, starts to open the valve,

the magn and, if switch K is open, as shown, continues operating until the valve reaches its other extreme position. At this point the motor is stalled, drawing an excess of current and actuating overload magnet F. This magnet then draws .up its contacts, breaking the circuit of magnet D, so as to release switch C, which returns to its oil-position, breaking the motor circuit. If switch C is moved to its other osition both magnets E and E are energizer so that the motor is again connected to the line-wires L, but with its armatures reversed, so that it drives the valve in the opposite direction.

As long as switch K is open the apparatus acts simply to break the motor circuit on an overload, and consequently to stop the motor when the valve reaches each extreme of its movement. Since the motor circuit is o ened only upon excessive current-flow, a big torque is produced for efiectually seating the valve.

In order to stop the valve at any intermediate position, th'ejcontact member h is first set at the position desired and switch K is then closed. If the position of contact h does not correspond to the position of contact 9, then current will flow between the two, energizing magnet I, and causing it to lift its contact so as to break the shortcircuit, which would otherwise exist around et D.. Switch v,C may then be closed and locked in position by magnet D,

thereby starting the motor; but when the valve-spindle reaches a position bearing a certain relation to the position of contact h, the contacts 9 and it will be at approximately the same potential, so thatmagnet I will be denergized, allowing its contact to fall. This closes a short-circuit around magnet D, which releases switch C, so as to break the motor circuit. Since the voltmeter J is connected between one linewire and the contact member 9, the voltage at its terminals corresponds to the position of the valve-spindle, and the reading of the voltmeter serves as an indication of the position of the valve.

What I claim as new and desire to secure by Letters Patent of the United States, is,'

1. In combination with an electric motor and a member driven thereby, a controlling switch for the motor biased to off position, electromagnetically operated means for holding said switch in an on position, an overload relay for rendering inoperative said electromagnetically o erated means upon an excess current flow t rough the motor, and another relay arranged when den ergized. to render inoperative said electro-' magnetically operated means, an actuating coil for s'aidlast mentioned relay, and means for energizing said coil and automatically maintaining it energized until said member has moved to any desired position.

2. In combination an electric motor and a member driven thereby, a controlling switch for the motorbiased to 0d position, a locking coil for holding said switch in an on position, an overload relay for interrupting the circuit through said locking coil upon an excess current flow through the motor, and another relay arranged when deenergized to short-circuit said locking coil, an actuating coil for said last mentioned re lay, and means for energizing said actuating coil and automatically maintaining it energized until said member has moved to any desired position. '3. In combination with an electric motor and a member driven thereby, a controlling switch for the motor biased to off position, a locking coil for holding the said switch in an on position, an overload relay arranged to render said locking coil inoperative upon an excess currentflow through said motor, two resistances connected in parallel across a source of current, one being adjacent s'aid driven member and the other adjacent the controlling switch, contact means operated by said driven member in its movement for making electrical connection at different points in said firstmentioned resistance, a manually movable contact member for making electrical connection at different points in the second'mentioned resistance, a relay having its actuating coil connected between said contact means operated by the driven member and the manually movable contact member, and arranged in one position to render said locking coil inoperative.

4. In combination with an electric motor and a member driven thereby, a controlling switch for the motor biased to ofi position, a locking coil for holding the said switch in an on position, an overload relay ar ranged to interrupt the circuit through said locking coil upon an excess current flow through said motor, two resistances connected in parallel across a source of current, one being adjacent said driven member and the other adjacent the controlling switch, contact means operated by said driven mem ber in its movement for making electrical connection at different points in said first mentioned resistance, a manuallyqmovable contact memberfor making electrical connection at different points in the second. mentioned resistance, a relayihaving its actuating coilconnected between said contact member and arranged in one position to short-circuit said locking coil.

In witness whereof, I have hereunto set my hand this 13th day of October, 1906.

SAM H. KANMAonEn.

Witnesses: BENJAMIN B. HULL, .HELEN ORFORD.

means and the manuallymovable contact 

